Approximately 10-15% of all infants pass meconium or fetal stools while still in the womb. Meconium is thick viscous particulate fluid. This condition is often due to the fetus experiencing a degree of hypoxia or lack of oxygen before birth. A serious problem faced in the delivery room during the birthing process involves the resuscitation of infants who have passed meconium in utero so that the meconium is aspirated into the pharynx and the trachea of the infant. Meconium aspiration can cause severe respiratory distress, and if the meconium is not thoroughly removed from the infant's air passageway, that is, the pharynx and trachea, before the infant begins to breath, there is a danger of developing illnesses such as pneumonia, sepsis, pneumothorax and persistent pulmonary hypertension which could result in the severe damage or death of the infant.
The presently accepted method of resuscitation of neonatal or newborn infants with meconium in their pharynx and trachea is set forth in the MANUAL OF NEONATAL CARE by Cloherty and Stark, Second Edition, Little Brown and Company, pages 203 to 206 (1985). The method involves a tedious procedure of suctioning the meconium out of the infant's pharynx and trachea by mouth, through an endotracheal tube (ETT).
In this procedure, a physician in one hand operates a laryngoscope, an instrument having a handle attached to a metal blade, which is inserted in the patient's mouth to open the patient's mouth. Any fluid is then suctioned from the mouth using a catheter which is in the physician's other hand. When the fluid is cleared from the mouth, the physician removes the catheter, puts it down and picks up an endotracheal tube. At this point, the metal blade portion of the laryngoscope is positioned in the patient's mouth to deflect the tongue and epiglottis in order to visualize the vocal cords. The endotracheal tube is inserted past the epiglottis, through the vocal cords and into the trachea. The laryngoscope is then removed from the patient's mouth to free the physician's hand to remove the stylet which is inside the passageway of the endotracheal tube. The stylet maintains the rigidity of the endotracheal tube while it is being inserted into the air passageway. While the stylet is necessary to maintain the rigidity of the endotracheal tube to assist in directing the tube past the vocal cords, the stylet must be removed from the tube after intubation in order to clear the tube to suction meconium. At this point, the physician suctions the trachea of the infant by mouth, through the endotracheal tube, to remove the meconium while withdrawing the tube. The proximal end of the endotracheal tube, which is in the physician's mouth, may be covered by a piece of gauze or by the physician's surgical mask while suctioning, to avoid contact with the meconium. However, the gauze or mask does not totally protect the physician from getting meconium into his mouth. Once the tube is withdrawn from the infant's mouth, the endotracheal tube must be cleared of meconium by blowing through the tube, and the stylet again reinserted so the procedure may be repeated. Alternatively, two or three additional endotracheal tubes and stylets must be immediately available. The laryngoscope must then be reinserted into the infant's pharynx and the entire intubation and suctioning procedure must be repeated in order to remove the meconium thoroughly. Typically, this procedure is repeated two to four times.
Once the meconium is cleared from the infant's trachea, the patient requires ventilation to provide oxygen to, and remove carbon dioxide from, the lungs. While this can often be done with an ambu bag and mask, it is far more effective to reintube the infant. Using currently accepted methods, the endotracheal tube must be cleared of meconium by blowing through the tube and the stylet reinserted, or, alternatively, an additional endotracheal tube and stylet is utilized. The laryngoscope is again repositioned in the mouth to visualize the vocal cords. The patient is then intubated and the laryngoscope is removed so the physician can remove the stylet with his free hand. The patient then may be ventilated using an ambu bag, which is attached to the endotracheal tube, to pump air through the larynx and trachea into the lungs. If the patient's heart rate is still slow, the ambu bag is removed from the endotracheal tube and medication is administered directly through the endotracheal tube. The ambu bag is then reattached to the endotracheal tube to force the medication into the infant's lungs and provide further ventilation.
The above-described procedure to remove meconium has several drawbacks. It is very inefficient in that it takes many steps to perform thoroughly and takes a relatively long period of time. Meconium must be removed from the pharynx and trachea of an infant before the infant takes its first breath. The longer it takes for the infant to start breathing, the higher the risk of brain, heart, kidney or other organ damage. Another problem resulting from the use of this method is the risk to the physician suctioning the meconium by mouth through the endotracheal tube. While it is common to put a gauze or surgical mask over the end of the endotracheal tube and suck through the gauze pad or surgical mask, there is still a danger of having the meconium come in contact with the physician's mouth. If this happens, serious infectious agents such as gonorrhea, hepatitis, or AIDS may be transmitted to the physician. This risk is especially acute in dealing with infants born to intravenous drug users, since a substantial number of them, perhaps as many as 75%, carry the HIV (AIDS) virus, which is present in body fluid such as meconium. This is a particular problem for pediatricians and other health care professionals involved in neonatal resuscitation who are routinely called into the delivery room shortly before or just after an infant is born and has developed a problem. In the emergency, it may be impossible to brief the pediatrician or other health care professional on the entire medical history of the infant's mother.